Evidence of Entanglement
This summer, like every summer over the past seven years, biologists (and BCCSN observers) Christie McMillan and Jackie Hildering spent their time documenting the comeback of humpback whales off Northeastern Vancouver Island. Humpbacks were wiped out of the area by commercial whaling; records indicate at least 5916 humpbacks were taken in BC waters between 1908 and 1967. Luckily, in the last 10 years, these animals have made an incredible comeback. In the summer of 2010, 38 individuals spent time around the Johnstone Strait /Blackfish Sound area where McMillan and Hildering work. Some of the animals are familiar, returning to the area year after year, while others are new. McMillan and Hildering know this because part of their study is a long-term photo identification project. By taking photos of the tail flukes (and flanks) of the animals they encounter, they can recognize each individual by its unique markings and fluke shape (see this earlier post to learn more about photo identification).
While this dedicated recording of humpback whales has allowed these biologists to better understand the comeback of this population, it has also revealed that humpbacks are still facing anthropogenic threats. This summer, one animal observed by McMillan and Hildering showed evidence of one such threat: entanglement in fishing gear.
The whale in question is a new to the area. Nicknamed ‘Sharktooth’ (because of its markings) until it can receive an official ID number by Fisheries and Oceans Canada, the whale visited the study area on two occasions throughout the summer and early fall. When first sighted between June 17th and 20th, Sharktooth appeared healthy. Unfortunately, the next time McMillan and Hildering saw ‘Sharktooth’ on October 2nd, something had changed; they observed significant damage to the whale’s fluke and tail stock – evidence of entanglement. See images on the right by Hildering and Bruce Paterson to see the before and after.
Entanglement is not new on this coast, but it is still a very under-studied issue. As documented in an earlier post, one whale known as ‘Twister’(BCY0710) became entangled twice along this section of Vancouver Island in 2009. In fact, in 2009, fourteen reports of entanglements were received by Fisheries and Oceans Canada’s Marine Mammal Incident Response Network. Statistics for 2010 are still being summarized.
Fourteen entanglements may not seem like a lot for an entire coastline, but research from the other side of North America indicates that entanglements are significantly under-reported. A study done by Jooke Robbins of the Center for Coastal Studies in Provincetown, Massachusetts, showed that over 90% of entanglements go undetected or unreported. She investigated the true level of entanglement by not only looking at animals that had obvious gear on them (like ‘Twister’), but by also looking at scaring on humpbacks, just like those seen on ‘Sharktooth’. If a similar situation to the one Robbins found in the Atlantic exists in BC, there are likely many more potentially-fatal entanglements happening each year. Click here to learn more about ‘Sharktooth’ and entanglement research.
So what can you do to help reduce entanglement of large whales?
- Joining the Great Canadian Shoreline Cleanup each September; the national program removes debris (like lost nets and line) from beaches that could potentially entangle marine life.
-Report all sightings to the BC Cetacean Sightings Network. A better understanding of distribution and habitat use by cetaceans and sea turtles will help researchers identify areas where the possibility of entanglement may be more likely. Report your sightings here or by calling 1.866.I.SAW.ONE.
-Report all possible entanglements to the Marine Mammal Incident Reporting Hotline 1.800.465.4336